/*
* FreeRTOS Modbus Libary: A Modbus serial implementation for FreeRTOS
* Copyright (C) 2006 Christian Walter <wolti@sil.at>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
/* ----------------------- System includes ----------------------------------*/
#include "stdlib.h"
#include "string.h"
/* ----------------------- Platform includes --------------------------------*/
#include "port.h"
/* ----------------------- Modbus includes ----------------------------------*/
#include "mb.h"
#include "mbframe.h"
#include "mbproto.h"
#include "mbconfig.h"
/* ----------------------- Defines ------------------------------------------*/
#define MB_PDU_FUNC_READ_ADDR_OFF ( MB_PDU_DATA_OFF )
#define MB_PDU_FUNC_READ_DISCCNT_OFF ( MB_PDU_DATA_OFF + 2 )
#define MB_PDU_FUNC_READ_SIZE ( 4 )
#define MB_PDU_FUNC_READ_DISCCNT_MAX ( 0x07D0 )
/* ----------------------- Static functions ---------------------------------*/
eMBException prveMBError2Exception( eMBErrorCode eErrorCode );
/* ----------------------- Start implementation -----------------------------*/
#if MB_FUNC_READ_COILS_ENABLED > 0
eMBException
eMBFuncReadDiscreteInputs( UCHAR * pucFrame, USHORT * usLen )
{
USHORT usRegAddress;
USHORT usDiscreteCnt;
UCHAR ucNBytes;
UCHAR *pucFrameCur;
eMBException eStatus = MB_EX_NONE;
eMBErrorCode eRegStatus;
if( *usLen == ( MB_PDU_FUNC_READ_SIZE + MB_PDU_SIZE_MIN ) )
{
usRegAddress = ( USHORT )( pucFrame[MB_PDU_FUNC_READ_ADDR_OFF] << 8 );
usRegAddress |= ( USHORT )( pucFrame[MB_PDU_FUNC_READ_ADDR_OFF + 1] );
usRegAddress++;
usDiscreteCnt = ( USHORT )( pucFrame[MB_PDU_FUNC_READ_DISCCNT_OFF] << 8 );
usDiscreteCnt |= ( USHORT )( pucFrame[MB_PDU_FUNC_READ_DISCCNT_OFF + 1] );
/* Check if the number of registers to read is valid. If not
* return Modbus illegal data value exception.
*/
if( ( usDiscreteCnt >= 1 ) &&
( usDiscreteCnt < MB_PDU_FUNC_READ_DISCCNT_MAX ) )
{
/* Set the current PDU data pointer to the beginning. */
pucFrameCur = &pucFrame[MB_PDU_FUNC_OFF];
*usLen = MB_PDU_FUNC_OFF;
/* First byte contains the function code. */
*pucFrameCur++ = MB_FUNC_READ_DISCRETE_INPUTS;
*usLen += 1;
/* Test if the quantity of coils is a multiple of 8. If not last
* byte is only partially field with unused coils set to zero. */
if( ( usDiscreteCnt & 0x0007 ) != 0 )
{
ucNBytes = ( UCHAR ) ( usDiscreteCnt / 8 + 1 );
}
else
{
ucNBytes = ( UCHAR ) ( usDiscreteCnt / 8 );
}
*pucFrameCur++ = ucNBytes;
*usLen += 1;
eRegStatus =
eMBRegDiscreteCB( pucFrameCur, usRegAddress, usDiscreteCnt );
/* If an error occured convert it into a Modbus exception. */
if( eRegStatus != MB_ENOERR )
{
eStatus = prveMBError2Exception( eRegStatus );
}
else
{
/* The response contains the function code, the starting address
* and the quantity of registers. We reuse the old values in the
* buffer because they are still valid. */
*usLen += ucNBytes;;
}
}
else
{
eStatus = MB_EX_ILLEGAL_DATA_VALUE;
}
}
else
{
/* Can't be a valid read coil register request because the length
* is incorrect. */
eStatus = MB_EX_ILLEGAL_DATA_VALUE;
}
return eStatus;
}
#endif
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